1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
|
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
Gives a approximated number of how many records there is between two keys.
Used when optimizing querries.
*/
#include "myisamdef.h"
#include "rt_index.h"
static ha_rows _mi_record_pos(MI_INFO *info,const byte *key,uint key_len,
enum ha_rkey_function search_flag);
static double _mi_search_pos(MI_INFO *info,MI_KEYDEF *keyinfo,uchar *key,
uint key_len,uint nextflag,my_off_t pos);
static uint _mi_keynr(MI_INFO *info,MI_KEYDEF *keyinfo,uchar *page,
uchar *keypos,uint *ret_max_key);
/*
Estimate how many records there is in a given range
SYNOPSIS
mi_records_in_range()
info MyISAM handler
inx Index to use
min_key Min key. Is = 0 if no min range
max_key Max key. Is = 0 if no max range
NOTES
We should ONLY return 0 if there is no rows in range
RETURN
HA_POS_ERROR error (or we can't estimate number of rows)
number Estimated number of rows
*/
ha_rows mi_records_in_range(MI_INFO *info, int inx, key_range *min_key,
key_range *max_key)
{
ha_rows start_pos,end_pos,res;
DBUG_ENTER("mi_records_in_range");
if ((inx = _mi_check_index(info,inx)) < 0)
DBUG_RETURN(HA_POS_ERROR);
if (fast_mi_readinfo(info))
DBUG_RETURN(HA_POS_ERROR);
info->update&= (HA_STATE_CHANGED+HA_STATE_ROW_CHANGED);
if (info->s->concurrent_insert)
rw_rdlock(&info->s->key_root_lock[inx]);
switch(info->s->keyinfo[inx].key_alg){
#ifdef HAVE_RTREE_KEYS
case HA_KEY_ALG_RTREE:
{
uchar * key_buff;
uint start_key_len;
key_buff= info->lastkey+info->s->base.max_key_length;
start_key_len= _mi_pack_key(info,inx, key_buff,
(uchar*) min_key->key, min_key->length,
(HA_KEYSEG**) 0);
res= rtree_estimate(info, inx, key_buff, start_key_len,
myisam_read_vec[min_key->flag]);
res= res ? res : 1; /* Don't return 0 */
break;
}
#endif
case HA_KEY_ALG_BTREE:
default:
start_pos= (min_key ?
_mi_record_pos(info, min_key->key, min_key->length,
min_key->flag) :
(ha_rows) 0);
end_pos= (max_key ?
_mi_record_pos(info, max_key->key, max_key->length,
max_key->flag) :
info->state->records+ (ha_rows) 1);
res= (end_pos < start_pos ? (ha_rows) 0 :
(end_pos == start_pos ? (ha_rows) 1 : end_pos-start_pos));
if (start_pos == HA_POS_ERROR || end_pos == HA_POS_ERROR)
res=HA_POS_ERROR;
}
if (info->s->concurrent_insert)
rw_unlock(&info->s->key_root_lock[inx]);
fast_mi_writeinfo(info);
DBUG_PRINT("info",("records: %ld",(ulong) (res)));
DBUG_RETURN(res);
}
/* Find relative position (in records) for key in index-tree */
static ha_rows _mi_record_pos(MI_INFO *info, const byte *key, uint key_len,
enum ha_rkey_function search_flag)
{
uint inx=(uint) info->lastinx, nextflag;
MI_KEYDEF *keyinfo=info->s->keyinfo+inx;
uchar *key_buff;
double pos;
DBUG_ENTER("_mi_record_pos");
DBUG_PRINT("enter",("search_flag: %d",search_flag));
if (key_len == 0)
key_len=USE_WHOLE_KEY;
key_buff=info->lastkey+info->s->base.max_key_length;
key_len=_mi_pack_key(info,inx,key_buff,(uchar*) key,key_len,
(HA_KEYSEG**) 0);
DBUG_EXECUTE("key",_mi_print_key(DBUG_FILE,keyinfo->seg,
(uchar*) key_buff,key_len););
nextflag=myisam_read_vec[search_flag];
if (!(nextflag & (SEARCH_FIND | SEARCH_NO_FIND | SEARCH_LAST)))
key_len=USE_WHOLE_KEY;
pos=_mi_search_pos(info,keyinfo,key_buff,key_len,
nextflag | SEARCH_SAVE_BUFF,
info->s->state.key_root[inx]);
if (pos >= 0.0)
{
DBUG_PRINT("exit",("pos: %ld",(ulong) (pos*info->state->records)));
DBUG_RETURN((ulong) (pos*info->state->records+0.5));
}
DBUG_RETURN(HA_POS_ERROR);
}
/* This is a modified version of _mi_search */
/* Returns offset for key in indextable (decimal 0.0 <= x <= 1.0) */
static double _mi_search_pos(register MI_INFO *info,
register MI_KEYDEF *keyinfo,
uchar *key, uint key_len, uint nextflag,
register my_off_t pos)
{
int flag;
uint nod_flag,keynr,max_keynr;
my_bool after_key;
uchar *keypos,*buff;
double offset;
DBUG_ENTER("_mi_search_pos");
if (pos == HA_OFFSET_ERROR)
DBUG_RETURN(0.5);
if (!(buff=_mi_fetch_keypage(info,keyinfo,pos,DFLT_INIT_HITS,info->buff,1)))
goto err;
flag=(*keyinfo->bin_search)(info,keyinfo,buff,key,key_len,nextflag,
&keypos,info->lastkey, &after_key);
nod_flag=mi_test_if_nod(buff);
keynr=_mi_keynr(info,keyinfo,buff,keypos,&max_keynr);
if (flag)
{
if (flag == MI_FOUND_WRONG_KEY)
DBUG_RETURN(-1); /* error */
/*
Didn't found match. keypos points at next (bigger) key
Try to find a smaller, better matching key.
Matches keynr + [0-1]
*/
if (flag > 0 && ! nod_flag)
offset= 1.0;
else if ((offset=_mi_search_pos(info,keyinfo,key,key_len,nextflag,
_mi_kpos(nod_flag,keypos))) < 0)
DBUG_RETURN(offset);
}
else
{
/*
Found match. Keypos points at the start of the found key
Matches keynr+1
*/
offset=1.0; /* Matches keynr+1 */
if ((nextflag & SEARCH_FIND) && nod_flag &&
((keyinfo->flag & (HA_NOSAME | HA_NULL_PART)) != HA_NOSAME ||
key_len != USE_WHOLE_KEY))
{
/*
There may be identical keys in the tree. Try to match on of those.
Matches keynr + [0-1]
*/
if ((offset=_mi_search_pos(info,keyinfo,key,key_len,SEARCH_FIND,
_mi_kpos(nod_flag,keypos))) < 0)
DBUG_RETURN(offset); /* Read error */
}
}
DBUG_PRINT("info",("keynr: %d offset: %g max_keynr: %d nod: %d flag: %d",
keynr,offset,max_keynr,nod_flag,flag));
DBUG_RETURN((keynr+offset)/(max_keynr+1));
err:
DBUG_PRINT("exit",("Error: %d",my_errno));
DBUG_RETURN (-1.0);
}
/* Get keynummer of current key and max number of keys in nod */
static uint _mi_keynr(MI_INFO *info, register MI_KEYDEF *keyinfo, uchar *page,
uchar *keypos, uint *ret_max_key)
{
uint nod_flag,keynr,max_key;
uchar t_buff[MI_MAX_KEY_BUFF],*end;
end= page+mi_getint(page);
nod_flag=mi_test_if_nod(page);
page+=2+nod_flag;
if (!(keyinfo->flag & (HA_VAR_LENGTH_KEY | HA_BINARY_PACK_KEY)))
{
*ret_max_key= (uint) (end-page)/(keyinfo->keylength+nod_flag);
return (uint) (keypos-page)/(keyinfo->keylength+nod_flag);
}
max_key=keynr=0;
t_buff[0]=0; /* Safety */
while (page < end)
{
if (!(*keyinfo->get_key)(keyinfo,nod_flag,&page,t_buff))
return 0; /* Error */
max_key++;
if (page == keypos)
keynr=max_key;
}
*ret_max_key=max_key;
return(keynr);
}
|
